Repeater arrant ement for multiplex signaling



Jan. 29, 1924.. 1,481,831

C. 8 DEMAREST REPEATER'ARRANGEMENT FOR MULTIPLEX SIGNALING Filed Sept.13 1919 3 Sheets-Sheet 1 mommy INVENTOR.

Jan. 29 1924. 1,481,831

- c. s. DEMAREST REPEATER ARRANGEMENT FOR MULTIPLEX SIGNALING FiledSept; 15 1919 3 Sheets-Sheet 2 zuaaaooo 284750000" 1 2 M? 1 2 g m M gg a4 1 17;

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591040000 50040000 F5 mg Y m1, m; a L- 1 r INYENTOR.

- & ATTORNEK Jan. 29 1924. 1,481,831

c. s. DEMAREST REPEATER Anameau'iw FOR MULTIPLEX smmmue Filed Sept 131919 3 Sheats-Sheet 5 gamma 31920000 1N VEN TOR.

c ATTORNEY 6 (ll certain Improvements in raug-ements for MultiplexSignaling, of. which the b repeater or p repeater units PatentedJan. 29,1924.

UNITED STATES CHARLES S. DEMARES'I', OF BROOKLYN, NEW YORK. ASSIGNOR TOAMERICAN PATENT OFFICE.

IEHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

REPEATER ARRANC EMENT FOR MULTIPLEX SIGNALING.

Application filed September 18, 1919. Serial No. 323,492.

To all whom it may concern:

Be it known that I, CHARLES S. DEMAREST, residing at Brooklyn, in thecounty of Kings and State of ew York have inventliepeater Arfollowing isa specification.

his invention relates to signaling systems and more particularly torepeating apparatus for such systems.

)ne of the. main features of the invention is the provision of arepeating apparatus of such character that the balancing equipmentusually provided in connection with two-way repeaters may be eliminated.

Another feature of the invention relates e provision of a repeatingsystem in which transmission in takes place at different amplified byone repeater or set of repeaters only, While frequencies transmitted inthe opposite direction are amplified by another peaters that thetransmission and amplificaf each range of frequencies can be regulatedindependently.

till another feature of the invention is the provision of a repeaterarrangement foi' a multiple frequency system of such character that therange of operation may be intreased without These results, as well asother aims of the invention, which will be clear from the detaileddescription hereinafter appearing, which one or more signalssimultaneously transmitted in utilize a plurality of carrier frequencieslying within one range, while one or more signals simultaneouslytransmitted in the-opposite direction utilize a corlying within anotherrange. In order to amplify theoppdsitely directed transmission one-wayrepeating apparatus (which may comprise a single repeater unit orseparate forann lit'ying the frequencies of difi'erent signa stransmitted in the same direction) is provided for the purpose Theinvention may now of amplifying frequencies within the range utilizedfor transmision in one direction. By associating properly designedfilters with th peating. apparatus, frequencies transmitted in theopposite direction will be prevented from reacting upon this one-wayrepeating apparatus, so that it is possible to directly associate theinput and output circuits of the two sets of repeating apparatus forrepeating in opposite directions, out using artificial lines orbalancing networks to prevent singeing.

be more fully understood from the following description, hen read inconnection with the accompanying drawing, Figures 1 and 2 when takentogether, constitute tion and Figs. 1 and 3 of which, when takentogether, constitute a circuit diagram of another emhodiment of theinvention.

et'erring to Figs. 1 and 2, ML designates a transmission lineterminating in carr1er apparatus, as shown in Fig. .1. The terminalcarrier apparatus is of a wellknown character and 15 not a part of theso tnat consequently it is merely illustrated in schematic form. L 1 andL, designate Signaling circuits rom which signals may he simultaneouslytransmitted over the main line ML. The signals transmitted over theselines may he telephonic, telegraphic or of any other character which itis desired to transmit. and the of signaling circuits may vary ascircumstances may require. The line L, is associated with a carriertransmitting:

present invention.

circuit TL and a carrier receiving circuit RL, through a balancedtrzu'isformer arrangement 11, said conjugate. so that disturbances inthe one do not affect the other, by balancing the line 1 br g leans ofan artificial line or net work in a similar manneg line L is associatedwith circuits TL and RL line L is associated with TL, and R and line Lis associated with circuits T11 and RL In order to translate the signalsincoming from the lines L L etc. into carrier can rents. modulators M MM and provided, each modulator being supplied by a source of carriercurrents, the several that, as LRustrated all of sources being. ofdifferent fre uencics. As illustrated, the fre uencies of the severalmodulators are 5,0 0, 10,000, 15,000 and 20,000 cycles respectively.These modulators may be of any well-known type, but are preferablymodulators of the well-known vacuum tube type.

The filters T1 and TF, are also provided in the circuit while anamplifier TA, is connected between said filters. These filters arepreferably of the type disclosed in the U. S. Patents to George A.Campbell, 1,227,113i1nd 1,227,114, dated May 22, 1917, and are sodesigned as to transmit a range of frequencies in the vicinity of thebasic carrier frequency assigned to the channel, said range having awidth sufiicient to take care of the frequency variation due to the lowfrequency signals. The amplifier TA, ma be of any well-known type, butis pre era ly a vacuum tube amplifier such as is well-known in the art.Similar filters and amplifiers are provided in the circuits TL,., TL andTL except that the range of rc qlucncies transmitted by the filters inthe ifierent circuits will depend upon the basic fre uency assigned tothe channel.

e receiving channel BL, includes filters RF, and R1 1, demodulator ordetector D and amplifier 3A,. The demodulator or detector D, may be ofany well-known character, but is preferably a detector of the vacuumtube type, employing the homodync method of receiving. The demodulatoror detector is therefore supplied with oscillations from a local source,having; the same ire uency.as the basic frequency of the mo ulatedreceived oscillations. In the case illustrated, the frequency assignedto the channel and therefore the frm uency of the local sour is 25,000cycles. The filters RF and RF, are similar to the corresponding filtersof the transmitting channel, except that the range of frequenciestransmitted by the former is in the neighborhood of 25,000 cycles,instead of in the neighborhood of 5.000 cycles, while fillers RF, is alow pass f lter transmitting only signaling frequen cies. It will thushe secn that the trans niitting and receiving channels operate atdifferenL frequencies, so that frequency separation as well as balanceis availa lc to prevent interaction of thc transmitting and receivingcircuits. The amplifier RA, is similar in all respects to the amplifierTA,, except that it is designed for amplifying low frequencies. Similarfiltering, demodulating and amplifying arrangements arc rovided for theother receiving channels -L,,, BL, and BL,. Basic frequencics assignedto the other channels are, however,

as illustrated, 30,000, 35,000 and 40.000 cycles for the receivingchannels RL,, RL.

and Rb,, lespectively. It will he oliserved the frequencies used fortransmitting lie in a ran e between 3,000 and 20,000 cycles, while therequencics used for reception lie betwcen 23,000 and 40,000 cycles. Thisprovides a very L()ll siderahle frequency separation between corrcspolu'ling transmitting and receiving channels of lhe same lowfrequency signaling circuit.

The transmitting channels 'lL,, 'lL. TI, and TL, are associated with acommon transmitting circuit TL and in a similar manner the receivingchannels RL,, liL. KL, and R L, are associated with a common receivingcircuit FL. The circuits TL and IL are associated with the main line MLthrough transformcrs 20 and 21, so that the tram mission from theseveral channcls may sl inultancously take place over the main linc.

One form of amplifying arrangement is illustrated in Fig. 2, in whichthe main line ML is conncctcd to the main lino sccliou ML by means of aplurality of rcpcatcvs 15A,, llrl EA, and li.\,, for transmission fromwest to cast, a similar sc: of one-way repeaters hi WA \VA, and \VA,being provided for amplifying trans missions from cast to west. Each ofthese repeaters isprct'erahly a vacuum tube rc. pcatcr of wcll knowutype, as illustrated in connection wil h the repcatcrs EA, and \V A thercmaining repcutcru hciug merely illus lratcd schcmatically. Filters arcprovided in the input and out put circuits of each oncway rcpcatcr fordctcrmining the frequen cies which will be transmitted to the rc--pcatcl' for amplification. Thus the amplifier EA, is provided withfilters El, and El in its input andoutput circuits, respectively, thcsctillers heing of the general character des ribed in the patents toCampbell aforementioned, and being so designed as to transmit a range offrequencies, for example from 3,000 to 5,000 cycles, which, it will henoted, corresponds to the frequencies used in transmitting from thetransmitting channel TL, of Fig. l. lhc correspoiuling repeater \VA, forrepeating in the opposite direction, is lllilWlSB provided with filters\VI, and \VF/ of the sonic general type, but in this inst ancc the rangeof frequencies transmitted is illustrated as being from 23,000 to 25,000cycles, (.Ol'lisllfilllllllg to the range of fretlpicncies assigned tothe receiving circuit ill, of Fig, 1. Similar filters are provided forall of thc, othcr oneway repeaters, as intlicalc and in cuch instancethe frequency range of the iiltcrs will corrcspond to the ll"(lllll(iyrangc of a cm'rcsponding transmitting; or receiving channel at thestation of Fig. 1. 5 w

The line ML will, of course, terminate in carrier apparatus similar tothat shown in Fig. 1. but r'or simplicity of illustration the carrierapparatu at the othcr station is not illustrutcd. it is not necessaryfcr a amplifying of the modulator M channel at the dista 23',O00 and25.000 cycles are impressed upon.

. receiving c of repeaters WA WA,

complete understanding of the invention. The operation is as follows:

Signals incoming from the line L are transmitted to the transmittingchannel TL through the transformer 11, modulating the carrier frequencyof 5,000 cycles by means The modulated freuencies are transmittedthrough the filter F amplified by the am lifier TA and then passedthrough the H ter TF to the common transmitting circuit TL. At the sametime similar operations may take lace with respect to the circuits L Land L The severaI modulated frequencies are now impressed throu the mainline the repeater L and are transmitte to apparatus of Fig. '2. Themodulated frequencies incoming from the transmitting channel TL areselected by means of the filterEF amplified by the amplifier EA andthen'passed through the 'filter EF. to the main line ML. In a similarmanner the modulated frequencies from the other transmitting channelsare selected and amplified by the circuits of the amplifiers E EA and EASignals from the distant station (not shown) associated with the mainline-ML are translatedinto frequencies lying in .a range from 23,000 to40,000 cycles-and are transmitted over the main line ML to the repeaterapparatus of Fig. 2. Modulated currents corresponding to onetransmitting 'ntstation are passed by the filter WF,, amplified by theamplifier WA and passed throu fortransnnssion over t e main line M L;other frequencies pass through the circuits an WA Upon arriving 'at the.station of'Fi 1 the several frequencies are transmitt through thetransformer 21 to the receiving circuit RL from which they are se aratedthrough the filters RF RF etc., of the receiving channels, The modulatedfrequencies. between the detector D and are thereby translated into lowfrequency si nals which are amplified by the ampli er RA and passedthrough .the low pass filter RF, to the line L The 0 erations inconnection with the annels' BT1 RL and RL are similar to those takingplace in connection with the receiving channel RL Since the frequenciesused in transmitting in one; direction lie' within an entirely differentrange from those used for transmitting in-the opposite direction, it ispossible, by use of a properly designed repeater, to amplify all of thefrequencies transmitted in one direction, by means of a commonamplifying arrangement. Fig. 3 illustrates an ;.arrangement for'thispurpose. ,In this insta. cc the transmission line ML is associated wi 1the transmission line ML through an h the transformer 20 u on 'lncomuligll 23,000 and' 40,000 cycles,

than those sh n many other or In order to' provide proper frequencyseparation between the repeaters, filters EF and EF' are associated withthe input and output circuits ofthe amplifier EA and filters WF- and WFare similarly associated with the amplifier VA. Thefilters EF and EF arearranged to transmit frequencies between 3,000 and 20,000 cycles, sothatall of the fre from transmitting chann s TL TL,, T and TL of Fig; 1may be passed to thqtmplifier EA and amplified thereby.

Filters W and WF' have a range between so that'all of the frequenciestransmitted in the op osite directlon to the receiving channels L RL,,RL,,, and RL of Fig. Lare amplified by the filter WA.

The operation of the arrangement shown in Figs. 1 and? will be obviousand need not be further described. It will be seen .85 quencies e thatno arrangementfor balancing the transmission line sections is provided.in.connection ,with the repeater arrangement of Fig. 3, since thefrequency separation due to the filters is sufiicient to preventsingeing over the circuit including the repeaters E and WA in series.The same statement applies to the repeater arrangements of ig. 2, inwhich all of the re eater circuits are separated by means of lters,so'that no.

slngeing circuit can be for ed t hrough a y two repeaters in series.

It will be understood that the frequencies disclosed herein are forpurposes of illus-' tration merely. and that other fre uencies own maybe used, if esi ed.

It will be also understood that the 31 na ing channels shown may beutilized or the transmission acter although, as illustrate the channelsare primari 'y designed for multiplextelephone transmission.

: II; will also principles herein disclosed may be em odied ani'zationswidely difi'eru'strated, without departent from those il ing from the sirit of the invention as do fined in the fol owing claims.

What is claimed is: 1. In a 'signalin (line, means for simultaneouslytransmitting over 'gaid line in one direction'ifplurality be obviousthat the neral of signals of an desired charg system, a transmission?? 7of signals lay means of elll'l't'lilH of dill'e rent frequencies. meansfor s-amultam-oimly transmitting in the opposite direclion over said"line a plnl'alily of signals by means of cur- "cola-a of a plurality ofother freqnem-ies. n eommon repeater in said line for amplifying all ofthe frequen ies transmitted in one. direction. and a .-cro .-l commonreprater for nmplil'yilyg-allol' the frequencies transmitted in theopposite direellon.

2. [n a signaling system. a transmission line. means For aimnllaneoimlytransmitting in one-direction over said line a plurality of signals liynn-usis of (,tll'l'tlllh of, n plurality of frequencies lying Within onefrequency range, nn-ans for simultaneously transmitting in the oppositedirection over said, line a plurality of signals by means of currents ofdifferent frequencies lying within another frequency range. a 0newnyrepeater apparatus for nmplrfying currents trai'ismitted over said linein one direction, a. second one-wily repeater apparatus for amplifyingrnrrents transmitted over said line. in the opposite. (lll'H'llUlL a,broad band a, \'e 'filtcrassociated with .said firstmentioned-rq'ieal'ing apparat-Imi'or freely trans; {nit-ting to therepeater withinsaid first mentioned range. while.

substantially SllPjjl'OSfillig frequencies lying without said range. anda'sccoiid broad hand a e f ller associated with said Ht'l'iilltlmenticned repealing! apparatus for freelv trunninittilig thereto 1" rrqiiencies lying within said second mentioned frequency range. whilesubstantially prcrcntingzthe transmission of frequencies lying withoutsaid range.

3. In a signaling systennin which signals;

are transmitted in opposite direetioiis by means of currents ofdifferent frequencies. a repeater apparatus comprisingone-way repeatersfor repeating oppositely directed transmissions.the input and outputcircuits of said one-way repeaters being so rue- 0- ciated. with eachother and with the transmission medium -of' the-systein that'energy maylie freely transmitted from the. output. circuit of inierepeater .to-thcinput, circuit 'ofthe othera'epeateig and meanz associated qnenyics'used or the tranmninsiou of signals inthc dim-etion in which the otherrepeater ainnlifies. i

4., T'n a signaling; system. a transmissimr 'linc. LlIt'IIIIS' dill'ereul, frequ ncy r;i nge. reheat ingaipnaquencie-s lyin -pvnler insaid line comprising fro llencies lvm rains in said line for amplifyingcurrents within the one frequency range, and another repeal ingapparatus for transmitting can rents lying within the other frequencyrange. r t I 5. In a signaling system, a transmission line. means forsimultaneously transmitting over said line a, plurality of signal bymeans of currents of a'plnrality of fremeans for simultaneouslytransmitting in the opposite direction over said line, 11 phi rnlity ofsignals by; means of currente bf different frequencies lyingwithin-another and entirely di'fi'erent frequency ran 6, n oonnnonrepeater for amplifying all 0 the frequencies within thefitstrndi'ltioned ran 0, and another common repehter for amp ifying all ofthe frequencieswithin the'secand range. 1 i (a. In a signaling, system atransmission line. means for transmitting one range of frequencies oversaid line in one .directiem means for transmitting another and entirelydifferent range of frequencies (war'saidline in the opposite direction;a two-wla retil-circuit for transmissionv in .one direction. and anothercircuit for transmission in the opposite direction; an amplifier in eacheircnit. andgsellectire means in one of said circuits on'each side ofthe amplifier therein. for passing the range ofh equencics need intranSmit-' ting in one direetiom and nrlcetiremeans in the. othercircuit on eat-h sidexof the amplifier therein, for stein-ting! thernngefof frequencies used in transn'iitti-ng iii-the.-o positcdirection. a

'7. In a signaling system a trans-mission line, means fortransmittingone range. of freqnenoiesover said'line in one direction.means for transmitting! another and entirely tllll cl'tlll l ftlllgt0ffrequencies ore-redid line in the opposite dirrctionra' twowrny fler'pealenin said linersaid repeater rotnprising; a. circuitfor;transmission, in" one dil reclion. and another "hir uit. fortranfiniis: sion in tho onposite ficr in ea -h circuit: a handfiltcntonz ea-eh side of then nplilier in one (tirenitjor -Ipasr ing:the rangigo-i 'lltqllljtt'lts transfnjiitted in withinone frequencyrange,

diree-tion an iunplll we one direction and suppressing the range-"onfret' ucncies transmitted in theyn pimsite ill-- recti on. and a handfil'tcron early SltlQD-fyllhfl amplifier in the other c'ir -nit' forfieely" tra nsn ittinsr the range 0 f; frequencies trtrns niittod n theopposite ire ctnim;and for suppress ng the; frequencies transmitted in;

the firsl directihm R. In a signaling systcnn transmission in! sections;mieway co -meeting the ends arm- 1 pat'hnnnd said.- llne Ftolitmsillnitransmission rtnay ftn c irai' fimisision giai'lia beg"; tween saidline sections.means for sn mtert place from one path t tho other uimnjt:hii",

transmission of energy over one of said paths to a line section,frequency selective means to limit to one of" said paths a range offrtumcncies transmitted in one direction over said lino sections, andfrequency sclec tire means to limit to the other path another andentirely different range of frequencies transmitted in the oppositx:direc tion over said lines.

9. In a signaling system, transmission line sections, one-waytransmission paths be tween said line sections, ineans for sointerconnecting the ends of said paths and said line sections thattransmission may take arrangements to place from one path to the otherupon the transmission of energy over one of said paths to a linesection, a band filter arrangement associated with one of Said paths andhaving a range of free transmission silch that frequencies transmittedover said line sections in one direction will be passed into said pathto the exclusion of the other path, and a hand filter arrangementassociated with the other path and having a different,

range of free transmission such that frequcncies transmitted over saidli nc.sect-ions 1n the opposite direction will be transmitted over saidpaths to the exclusion of said first mentioned path.

10. In a signaling system, transmission line sections over which aplurality of signals may be simultaneously transmitted in bothdirections, a circuit arrangement associated with said. line sectionsfor transmission in one direct-ion, another circuit arrangenientassociated with said line sections for transmission in the'oppositedirection,

means for 'so interconnecting said circuit arrangements with said linesections that transmission may take place from one circuit arrangementto the other upon the transmissionof energy over one of said circuit aline section, means for selecting into one of said circuit arrangementsa plurality of signals transmitted over said linesections in onedirection, and preventing transmission over said circuit arrangement ofsignals transmitted in the optween said line place from 'one path topositc direction, and means associated with the other circuit.arrangement ,for selecting into the said circuit arrangement-a pluralityof'signals transmitted in the opposite direction, while preventing thetransmission over said circuit arrangement of signals transmitted in thesaid first direction.

11. In a signaling system. transmission line sections, one-waytransmission paths besections, means for so interconnecting the ends of.said paths and said line sections that transmission may take the otherupon the over one of said ansmission of-energy one-way repeaters m pathsto a line Section,

-' 'eiiph of-said paths, selectivemeans in one of .said pathswherebxfiewencies transmitted over said line sections in one directionwill pass over said path to th exclusion of the other path, andselective means in the other path whereby frequencies transmitted oversaid line section in the opposite direction will pass over said path tothe cyclusion of said first mentioned path.

12: In a signaling system, transmission line sections, one-waytransmission paths between said line sections. means for sointerconnecting the-ends of said paths and said linc sections thattransmission may taltc place from one path to the other upon thetransmission of energy over one of said paths to a line section, one-wayrepeaters in eachpath, sclur-ti'vc devices in one of said paths on eachside of said repeater whereby frequencies transmitted over said line.sections in one direction will .pass over saidpath in the exclusion ofthe other path, and selective means in the other path on each side ofthe repeater therein whereby frequencies transmitted over said linesections in the opposite direction will pass over said path to theexclusion of said first mentioned path.

13. In a signaling system, transmission line sections, one-waytransmission paths between said line sections, means for sointcrconnecting the ends of said paths and said line sections thattransmission may take place -from one path to the other upon thetransmission of energy over one of said paths to a line section, one-wayrepeaters in each of said paths and band filters in 'one of said pathswhereby frequencies transmitted over said'line sections in onedirectionwill pass over said path to the exclusion of the. other path, and bandfilters in the other path Wherehy frequencies transmitted over said linesections in the opposite direction' will pass over said path to theexclusion of said first mentioned path.

14.,1'11 a signaling system, transmission line sections one-waytransmission paths between said line sections. means for so inter--connecting the ends of said paths and said line sections thattransmission may take place from one path transmission of. energy overone of said paths to a line section one-Way repeaters in each path.band. filters in one of said paths on each sideof said repeater wherebyfrequencies transmitted over said line sections to the other npon the.

','0n||( 'Iin;5 lhv vmls of said ml'hs am'l said Jim- H-miun lluntransmission may take place i'mm ummlll [u Huother upon theil'ansrliiss'iun Hf ('llll'; m'vn mm 01' said paths to Hm! lim-H('('|ill|l. l'm uullcy svleciivc medias h lnnil [H mm ul' mhl paths arange of fre- ('IHUIHIilh mrrospmuling to a plurality of rlmnnulstrans-mining in mm direction over -ni1i Haw wr'lilm. :uui frequencysvlwiive means to limit to the other path another 10 range offrequencies curresponding to u. plurality of (.ham'mls lramuilling inthe opposite direction over said line svcliion.

In testimony wlu-ruu-t', have signed my munu II: this .spwifivaliun thislilth (lay of is September, [919.

CH; RLIJH b. DEMAREST.

